A 16-year-old relative of missing 11-year-old Terry Smith of Menifee, Calif., has been arrested on suspicion of murder after a body matching Terry's description was found in a shallow grave behind his house, law enforcement authorities said.

Capt. John Hill of the Riverside County Sheriff's Department said at a news conference on Wednesday afternoon that the body matched the description of Terry but had not yet been positively identified, according to ABC's Los Angeles station KABC.

When Hill announced the arrest, he would not say if the family member arrested was Terry's 16-year-old half-brother who had allegedly been the last to see Terry before he disappeared.

"One of the things I want to stress is that this was a domestic issue within that residence, and that there is no stranger in the city of Menifee that caused this to happen," Hill said.

At around 1 a.m. on Wednesday, someone from the Smith home called police to report possible remains in the backyard, according to KABC. Police found a shallow grave about 75 feet from the house when they arrived.

The Sheriff's Department said the search for Terry had been suspended. Investigators served the Smith home with a search warrant, and Terry's mother, her partner and Terry's half-brother were interviewed, KABC reported.

"This week has been a devastating week for our family and for everybody involved in the search," the Smith family said in a statement. "This community has been amazing, and we appreciate all the support."

Investigators originally said Terry was last seen in his stepbrother's room around 9 p.m. Saturday and was gone by Sunday morning, according to KABC.

But the story changed on Wednesday when the brother allegedly told officials that Terry had followed him on the way to a friend's house the night he disappeared, and when he realized Terry was following him, he told him to go home, KABC reported.

The county sheriff's office had identified Terry as an "at-risk autistic child" in its missing person report, but his family and school seemed to disagree on that diagnosis.

"I know it's going to be a bit of a shock to people to hear this, but no, he was not autistic," Jenny Smith, who said she taught Terry, told KABC.

Police are asking anyone with information on the case to call the Riverside County Sheriff's Department at 951-776-1099.